Sunday, September 28, 2008

I think Mark Guzdial is really smart and really neat. So when he talks, I tend to think hard about what he has to say. Mark recently said some things that I would (VERY) roughly interpret to mean that programming is central to computer science. I also think Robb Cutler is really smart, and I know he disagrees. Robb thinks we could teach introductory CS at the K-12 level without any programming at all. This left me with a lot to think about, but finally I hit upon an analogy.

Programming is to computer science as experiments are to chemistry (or other sciences). It is THE central tool to the discipline. Being able to do it is an important skill. But it isn't actually central to the K-12 introductory experience. You could teach intro chemistry without doing any hands-on experiments. In some ways, the students would have a lesser experience, but most of them would be able to learn all the relevant concepts without actually doing them. Similarly, I think you could easily construct an introductory CS course that didn't have programming.

I agree with Robb that frequently the programming gets in the way of understanding. Kids get so caught up in debugging that they don't really understand the logic of the program. They lose sight of the problem that the program is supposed to solve because the problems that they're focused on are of the "it won't compile" variety. Who knows if the proposed solution (the program) is a good solution to the problem, we can't tell if it won't even run! (Okay, we the experienced programmers can tell. But the student can't.)

I was a biochemistry major and I took two years of high school chemistry (thus the root of my analogies!). I was a junior in college before I understood WHY you do experiments. It was all cookbook to me until then, completely disconnected from anything we learned in lecture. I figured they made you do it so you would have the experience of having done it so you could get a job following those kinds of instructions in the future. "Oh yes sir, I've done many titration experiments." I became a chemistry teacher and despite my experience, I advocate for having students do experiments.

There are many reasons for students to run experiments. It gives them lab skills which they can't get any other way - reading about titration is very different from actually having to work a stopcock correctly. For kids who are kinesthetic learners, or ones who need to SEE to understand, it helps them understand the concepts discussed in class. It can help them understand the scientific method in a different way and can help them understand the very nature of science research. (One of the reasons that I hated experimentation is that there's experimental error. It's all so beautiful and perfect in theory.) It's the same with programming and computer science. In introductory science classes, we use experiments judiciously, allowing students to gain the benefits but recognizing that there's a lot of material to cover and much of it is not best comprehended through direct experimentation. We should do the same with programming.

We should introduce students to programming as a tool without having it be the focus of introductory courses. Have them do it some, sure, but not at the expense of understanding the big ideas - most of which aren't about programming at all. Help students understand that programming is a tool, not an endpoint.

Over on Learning Curves, Rudibecka Hirta has a post about knitting and CS, complete with annotated pictures! (I can't figure out if it's overly friendly to call her 'Becky' or overly formal to call her 'Rudibecka') It reminds me of a SIGCSE a few years ago, when I was working on a not-very-complicated lace pattern during a luncheon, using a chart. Dave F got very excited about the pattern because it is digital. He couldn't get over how cool it is that knitting is digital.

It makes me both wonder how many really random intersections there are between hugely different ideas, and wonder if the reason why a lot of geeks I know are crafty is because there is a significant overlap in the kind of thinking between CS and crafts like knitting and quilting.

Friday, September 12, 2008

I'm at a meeting where I was asked to determine the big ideas in computer science. Big ideas are defined as the things students will internalize and remember long after a course is over. An example in calculus is that I remember what a limit is, even though I don't remember how to calculate one.

Here are the four big ideas I thought of:

Computer tools are designed and the design affects what they can do.

Computers precisely execute instructions created by humans.

This would include abstraction – what the instructions look like and how they are translated between layers.

It includes algorithm creation and predicting what the computer will do given a set of instructions.

It can include flow of instruction.

It MAY include programming.

Computers are used to solve many problems across many disciplines.

Ideally here students would design algorithms to solve various problems such as traffic flow, databases…

It would probably include the limit of computing – what problems are computers not good for solving and why.

Computing has a role in society

Ethics,

Use of the tool,

History of computing and how society has changed based on computing technology…